1. Field of the Invention
The present invention relates to a bio signal measuring apparatus and method, and more particularly, to an apparatus and method for measuring and analyzing an electrocardiogram and a heart sound.
2. Description of the Related Art
A QRS complex is a signal representing the contraction of a ventricle in an electrocardiogram signal and is required for evaluating a heart state of a user. Particularly, the R peak among QRST peaks composing the QRS complex must be accurately detected.
FIG. 1 shows a typical electrocardiogram signal. Portion “x” indicates the R peak signal and the interval between two R peaks is referred to as an RR interval. The RR interval is the period of time for measuring a heart rate and the R peak is counted during a predetermined period of time to measure the hear rate. Accordingly, the RR interval can be clinically used in arrhythmia diagnosis such as tachycardia, bradycardia, or premature ventricular contraction. Also, the RR interval can provide an index for predicting cardioplegia and an index for evaluating an autonomic nerve function to be applied for the stress evaluation. Also, using the RR interval, an optimal exercise intensity can be provided to the user and an amount of consumed calories can be calculated.
When the user is in a stable state, the R peak can be accurately detected from the electrocardiogram signal. However, when the user is in motion, the R peak can not be accurately detected because the electrocardiogram signal is largely influenced by a noise such as muscle noise, baseline fluctuation due to the breath, or power supply noise, as shown in FIG. 2.